src/app.css

/* src/app.css */
:root {
  --primary-color: #1976d2;
  --primary-hover: #1565c0;
  --background: #f5f5f5;
  --surface: #ffffff;
  --text-primary: #212121;
  --text-secondary: #666666;
  --border: #e0e0e0;
  --error: #d32f2f;
  --shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
  --shadow-hover: 0 4px 8px rgba(0, 0, 0, 0.15);
  --border-radius: 8px;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  padding: 0;
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
  background-color: var(--background);
  color: var(--text-primary);
  line-height: 1.6;
}

main {
  max-width: 600px;
  margin: 0 auto;
  padding: 2rem 1rem;
}

header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 2rem;
}

h1 {
  margin: 0;
  font-size: 1.75rem;
  font-weight: 600;
  color: var(--text-primary);
}

.refresh-btn {
  background: var(--primary-color);
  color: white;
  border: none;
  padding: 0.5rem 1rem;
  border-radius: var(--border-radius);
  cursor: pointer;
  font-size: 0.875rem;
  transition: all 0.2s ease;
}

.refresh-btn:hover:not(:disabled) {
  background: var(--primary-hover);
  transform: translateY(-1px);
}

.refresh-btn:disabled {
  opacity: 0.6;
  cursor: not-allowed;
}

.email-container {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.navigation {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1rem;
  background: var(--surface);
  border-radius: var(--border-radius);
  box-shadow: var(--shadow);
}

.navigation button {
  background: none;
  border: 1px solid var(--border);
  padding: 0.5rem 1rem;
  border-radius: var(--border-radius);
  cursor: pointer;
  transition: all 0.2s ease;
  font-size: 0.875rem;
}

.navigation button:hover:not(:disabled) {
  background: var(--background);
  border-color: var(--primary-color);
}

.navigation button:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

.counter {
  font-size: 0.875rem;
  color: var(--text-secondary);
  font-weight: 500;
}

.empty-state {
  text-align: center;
  padding: 3rem;
  background: var(--surface);
  border-radius: var(--border-radius);
  box-shadow: var(--shadow);
}

.empty-state h2 {
  margin: 0 0 0.5rem 0;
  color: var(--text-secondary);
}

.empty-state p {
  margin: 0;
  color: var(--text-secondary);
}

@media (max-width: 480px) {
  main {
    padding: 1rem;
  }

  h1 {
    font-size: 1.5rem;
  }

  .refresh-btn {
    padding: 0.375rem 0.75rem;
    font-size: 0.8125rem;
  }

  .navigation {
    flex-direction: column;
    gap: 1rem;
  }

  .navigation button {
    width: 100%;
  }
}